Stygimoloch

An Herbivorous PachycephalosauridStygimoloch, pronounced STIJ-eh-MOLL-uk, is generally regarded as a genus of large Pachycephalosaurid dinosaur, an herbivore (some regard Stygimoloch an omnivore). The genus received its name due the fearsome appearance of its skull. Only parts of Stygimoloch’s skull have been found to date, in Montana and Wyoming. Stygimoloch belongs to the family Pachycephalosauridae, which were Ornithischian dinosaurs that had thick, domed and spiked skulls.

What Did Stygimoloch Look Like?

Image Courtesy of Flickr User Adventures in Librarianship

The name Stygimoloch (meaning, Demon Of The River Styx) was given for the mean appearance of the specimen skull. It features three to four large spikes up to four inches (100 mm) long. Stygimoloch was a large Pachycephalosaur with a skull measuring 18 inches in length.

There was a lot of ornamentation at the top of the head of Stygimoloch, though smaller and shorter than other Pachycephalosauria. Its horns were conical, while the back corners of it’s triangular skull formed into large rearward spikes six inches long and two inches in diameter. Even around these spikes are other spikes, smaller. It is believed most likely that the horns and spikes were used primarily to garner effectiveness in jousting, through head-butting and flank-butting. In this case, the horns would certainly serve as ornamentation that could be helpful in identification and mating.

Pachycephalosauria are a thick-headed clade of dinosaurs, with domed skull-roofs that are usually several inches thick. In others (i.e.—Stygimoloch) the skull is flatter and wedge-shaped (triangular).

It should be noted here that some scientists theorize the flatter skulls to be representative of the youngest Pachycephalosaur dinosaurs, and that as adulthood manifests, the skulls become domed with maturity.

Most Pachycephalosaur lived in the Late Cretaceous, as Stygimoloch did

Triceratops is another Late Cretaceous ornithischian dinosaur that sported orbital/ cranial horns (similar generally horny cranial appearances), making them resemble today’s horny-toads, rhinoceros and ostrich. It was not until 1974 that Pachycephalosauria were first named as a suborder of the Order Ornithischia by Maryańska and Osmólska.

What Did Stygimoloch Eat?

Image Courtesy of Flickr User Paul Williams (Iron Ammonite)

While Stygimoloch is widely reported as an herbivore, it should be noted that some consider the genus to be omnivorous and that this idea is further supported by the Pachycephalosauria descriptions as a clade that were all bipedal and omnivorous.

A horizontal biped living during the Late Cretaceous Period, Stygimoloch could have eaten any of the angiosperms that were flourishing during the period. These flowering plants were largely responsible for the new lush lower landscapes (eventually grasses) that Stygimoloch probably also enjoyed. Stygimoloch may have also enjoyed the plentiful eggs found in nests as it foraged plant-life, along with the small marsupials and placental mammals. Snails, insects—anything small enough to be easy prey—would have been easy pickings for this quick genus.

How Did Stygimoloch Move?

Stygimoloch was a bipedal ornithischian dinosaur and as such was large and powerful in the hip (pelvic) region, with relatively long legs for its size. Its upper body was light in comparison, easing aerodynamic concerns and even though the head of Stygimoloch was long, it was relatively small and light. Stygimoloch would have been a fast and efficient plant-eating omnivore, which could possibly have also had a powerful loping or jumping gate—much like a kangaroo today.

The appearance of Stygimoloch is thought to have been mostly due to need of its own defense due to predation, along with basic social ritual. In times of defense, Stygimoloch was probably formidable enough, able to butt and gash the belly of any carnivorous predator, given the right angle. If one considers the top-head view that a predatory meat-eater would have seen if an unaware Stygimoloch had never noticed its presence and looked up, then one can see how the predator may have been deterred—it was almost a camouflage, and a horny spikey one at that.

Where Did Stygimoloch Live?

Fossils of Stygimoloch are found in the Late Cretaceous Period of North America, in what are known today as the states of Montana and Wyoming.

The Discovery of Stygimoloch

Image Courtesy of Flickr User j3tdillo

Stygimoloch takes its name from the Greek translation of “demon of the River Styx”—a name which refers primarily to appearance only, and is taken from legend (The River Styx separated the Earth from Hades in Greek Mythology.) Fossils were discovered in Hell Creek, Montana in 1983, and also in Wyoming. Stygimoloch was named in 1983 by British paleontologist Peter M. Galton and German paleontologist Hans-Dieter Sues.

Peter Galton helped champion the theory (cladistics theory 1974) that today’s birds are derived from prehistoric dinosaurs. He also showed that Hypsilophodon did not after all live in trees and that hadrosaur did not drag their tails but rather used them as counterbalances.

Stygimoloch, What Big Horns You Have

Although Stygimoloch had very large horns all over its bony head, it is believed to have been a largely passive herbivorous omnivore. Any real use of its horns and bony domed skull would have been either in defense from predators or in social activities with its own species.

The Significance of Stygimoloch

Stygimoloch seem to be significant in showing that during the Late Cretaceous Period, these were plant-eating creatures similar to our deer or kangaroo today in behavior and general appearance. Stygimoloch and the like help to show the diverse and yet somehow similar nature of prehistoric times, and help us learn about our own.